Watch out, Congress: Girl Up activists came to the nation's capital in June to lobby for issues affecting girls in the developing world. From left, Alexandra Leone (New Hope, Pa.), Grace Peters (Flemington, N.J.), Aklesiya Dejene (Chicago), Isabella Gonzalez and Erika Hiple (Stockton, N.J.) Ryan Kellman /NPR hide caption

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The human Y chromosome (left) holds the code for "maleness"; that's the X on the right. Andrew Syred/Science Source hide caption

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With Men's Y Chromosome, Size Really May Not Matter

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Hackers pose at Disrupt Hackathon in 2011. Araya Diaz/Getty Images hide caption

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